From: Sameer Pujar <email@example.com>
To: Dmitry Osipenko <firstname.lastname@example.org>,
Jon Hunter <email@example.com>, <firstname.lastname@example.org>,
Cc: <email@example.com>, <firstname.lastname@example.org>,
Subject: Re: [alsa-devel] [PATCH 4/9] ASoC: tegra: add Tegra210 based I2S driver
Date: Thu, 23 Jan 2020 14:52:14 +0530 [thread overview]
Message-ID: <email@example.com> (raw)
On 1/22/2020 9:57 PM, Dmitry Osipenko wrote:
> External email: Use caution opening links or attachments
> 22.01.2020 14:52, Jon Hunter пишет:
>> On 22/01/2020 07:16, Sameer Pujar wrote:
>>>>>>>>> +static int tegra210_i2s_remove(struct platform_device *pdev)
>>>>>>>>> + pm_runtime_disable(&pdev->dev);
>>>>>>>>> + if (!pm_runtime_status_suspended(&pdev->dev))
>>>>>>>>> + tegra210_i2s_runtime_suspend(&pdev->dev);
>>>>>>>> This breaks device's RPM refcounting if it was disabled in the active
>>>>>>>> state. This code should be removed. At most you could warn about the
>>>>>>>> unxpected RPM state here, but it shouldn't be necessary.
>>>>>>> I guess this was added for safety and explicit suspend keeps clock
>>>>>>> Not sure if ref-counting of the device matters when runtime PM is
>>>>>>> disabled and device is removed.
>>>>>>> I see few drivers using this way.
>>>>>> It should matter (if I'm not missing something) because RPM should
>>>>>> be in
>>>>>> a wrecked state once you'll try to re-load the driver's module. Likely
>>>>>> that those few other drivers are wrong.
>>>>> Once the driver is re-loaded and RPM is enabled, I don't think it
>>>>> would use
>>>>> the same 'dev' and the corresponding ref count. Doesn't it use the new
>>>>> If RPM is not working for some reason, most likely it would be the case
>>>>> for other
>>>>> devices. What best driver can do is probably do a force suspend during
>>>>> removal if
>>>>> already not done. I would prefer to keep, since multiple drivers still
>>>>> have it,
>>>>> unless there is a real harm in doing so.
>>>> I took a closer look and looks like the counter actually should be
>>>> reset. Still I don't think that it's a good practice to make changes
>>>> underneath of RPM, it may strike back.
>>> If RPM is broken, it probably would have been caught during device usage.
>>> I will remove explicit suspend here if no any concerns from other folks.
>> I recall that this was the preferred way of doing this from the RPM
>> folks. Tegra30 I2S driver does the same and Stephen had pointed me to
>> this as a reference.
>> I believe that this is meant to ensure that the
>> device is always powered-off regardless of it RPM is enabled or not and
>> what the current state is.
> Yes, it was kinda actual for the case of unavailable RPM.
> Anyways, /I think/ variant like this should have been more preferred:
> if (!pm_runtime_enabled(&pdev->dev))
I think it looks to be similar to what is there already.
pm_runtime_disable(&pdev->dev); // it would turn out to be a dummy call
if (!pm_runtime_status_suspended(&pdev->dev)) // it is true always if !RPM
>> Now for Tegra210 (or actually 64-bit Tegra) RPM is always enabled and so
>> we don't need to worry about the !RPM case. However, I still don't see
>> the harm in this.
> There is no real harm today, but:
> 1. I'd prefer to be very careful with RPM in general, based on
> previous experience.
> 2. It should be a bug if device isn't RPM-suspended during
> of driver's removal. Thus the real problem needs to be fixed
> rather than worked around.
next prev parent reply other threads:[~2020-01-23 9:22 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-20 14:23 [PATCH 0/9] add ASoC components for AHUB Sameer Pujar
2020-01-20 14:23 ` [PATCH 1/9] dt-bindings: sound: tegra: add DT binding " Sameer Pujar
2020-01-20 14:23 ` [PATCH 2/9] ASoC: tegra: add support for CIF programming Sameer Pujar
2020-01-20 15:58 ` [alsa-devel] " Dmitry Osipenko
2020-01-21 4:41 ` Sameer Pujar
2020-01-21 16:04 ` Dmitry Osipenko
2020-01-27 5:11 ` Sameer Pujar
2020-01-28 22:40 ` Dmitry Osipenko
2020-01-20 14:23 ` [PATCH 3/9] ASoC: tegra: add Tegra210 based DMIC driver Sameer Pujar
2020-01-20 14:23 ` [PATCH 4/9] ASoC: tegra: add Tegra210 based I2S driver Sameer Pujar
2020-01-21 5:15 ` [alsa-devel] " Dmitry Osipenko
2020-01-21 14:21 ` Sameer Pujar
2020-01-21 16:03 ` Dmitry Osipenko
2020-01-22 4:32 ` Sameer Pujar
2020-01-22 6:23 ` Dmitry Osipenko
2020-01-22 7:16 ` Sameer Pujar
2020-01-22 11:52 ` Jon Hunter
2020-01-22 16:27 ` Dmitry Osipenko
2020-01-23 9:22 ` Sameer Pujar [this message]
2020-01-23 15:16 ` Dmitry Osipenko
2020-01-24 9:07 ` Jon Hunter
2020-01-24 9:51 ` Jon Hunter
2020-01-24 14:04 ` Dmitry Osipenko
2020-01-27 5:22 ` Sameer Pujar
2020-01-29 3:41 ` Dmitry Osipenko
2020-02-14 14:05 ` Jon Hunter
2020-02-18 1:00 ` Dmitry Osipenko
2020-02-19 16:10 ` Sameer Pujar
2020-01-22 16:26 ` Dmitry Osipenko
2020-01-20 14:23 ` [PATCH 5/9] ASoC: tegra: add Tegra210 based AHUB driver Sameer Pujar
2020-01-24 1:18 ` [alsa-devel] " Dmitry Osipenko
2020-01-24 3:39 ` Sameer Pujar
2020-01-24 4:28 ` Dmitry Osipenko
2020-01-27 9:45 ` Jon Hunter
2020-01-20 14:23 ` [PATCH 6/9] ASoC: tegra: add Tegra186 based DSPK driver Sameer Pujar
2020-01-20 14:23 ` [PATCH 7/9] ASoC: tegra: add Tegra210 based ADMAIF driver Sameer Pujar
2020-01-24 1:28 ` [alsa-devel] " Dmitry Osipenko
2020-01-24 3:27 ` Sameer Pujar
2020-01-24 4:25 ` Dmitry Osipenko
2020-01-27 5:08 ` Sameer Pujar
2020-01-20 14:23 ` [PATCH 8/9] arm64: tegra: add AHUB components for few Tegra chips Sameer Pujar
2020-01-20 14:23 ` [PATCH 9/9] arm64: tegra: enable AHUB modules " Sameer Pujar
2020-01-28 10:49 ` [PATCH 0/9] add ASoC components for AHUB Sameer Pujar
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